Abdullah Saleh Aldwayyan

Methylammonium lead iodide (MAPbI₃) is a benchmark absorber for low-cost, high-efficiency perovskite solar cells (PSCs), but its practical deployment is constrained by small grain sizes, high defect densities, and moisture-sensitive surfaces that limit both efficiency and stability. Here, we demonstrate that covalent organic frameworks (COFs) built from commercially available building blocks provide a powerful, multifunctional route to overcome these limitations by simultaneously regulating crystallization, passivating defects, and tuning surface properties in MAPbI₃ thin films. Three hydrazone-linked and β-ketoenamine frameworks, denoted DMTH-COF, Boc-PDA-COF and Tp-COF, were prepared by condensing 2,5-dimethoxyterephthalohydrazide (DMTH), Boc-PDA-phenylenediamine (Boc-PDA), and 1,3,5-triformylphloroglucinol (Tp), respectively, and were incorporated at low loading into the MAPbI₃ precursor solution. X-ray diffraction and FE-SEM reveal that all three additives preserve the tetragonal perovskite phase while enlarging the grain size from a few hundred nanometers in pristine films to about 1 μm for DMTH-modified layers, accompanied by narrowed diffraction peaks and reduced microstrain. Raman and FTIR spectroscopy show COF-induced modifications of Pb–I and CH₃NH₃⁺ vibrational modes, indicating specific coordination and hydrogen-bonding interactions that stabilize the lattice and reduce trap density. UV-Vis spectra confirm strong visible-light absorption at an unchanged optical bandgap of 1.56 eV across all films, while steady-state PL and EQE measurements evidence enhanced radiative efficiency and improved photon-to-current conversion, particularly at longer wavelengths. X-ray photoelectron spectroscopy confirms that the framework is retained within the film after annealing, the modified absorber showing a N 1s component at 399.7 eV that is absent from the pristine reference, while the Pb 4f and I 3d core levels shift in parallel with their spin–orbit splittings preserved and no metallic lead detected. These material-level improvements translate into substantial device gains in n-i-p PSCs (FTO/c-TiO₂/m-TiO₂/COF:MAPbI₃/Spiro-OMeTAD/Au). Relative to pristine MAPbI₃ cells (PCE ≈ 14.7%), COF-modified devices exhibit higher Voc, Jsc, and FF, with DMTH-COF-modified cells achieving Voc = 1.183 V, Jsc = 22.98 mA cm⁻², FF = 76.46%, and PCE = 20.78%, alongside reduced series resistance, increased shunt resistance, and improved device-to-device reproducibility. Water-contact-angle and EDX analyses confirm that COF addition increases surface hydrophobicity and preserves near-ideal Pb:I stoichiometry, supporting enhanced environmental stability. This study introduces bulk COF doping as a simple, scalable strategy to engineer MAPbI₃ microstructure, energetics, and surface chemistry in a single processing step, and identifies DMTH-COF as the most effective of the three frameworks. More broadly, it positions COF–perovskite hybrids as a tunable platform for high-efficiency, durable perovskite optoelectronics.

Selenium‐tellurium (Se _{1‐ x} Te _x ) alloys offer promising potential for thin‐film photovoltaics owing to their tunable bandgap, low cost, and environmental sustainability. By tuning the Se:Te ratio, the bandgap of Se _{1‐ x} Te _x alloys can be adjusted to an optimal value (≈1.35 eV) which is crucial for approaching the maximum efficiency of a single‐junction solar cell. Which enhances solar absorption and increases power conversion efficiency (PCE). In this simulation‐based work, we provide a comprehensive study to design Se _{1‐ x} Te _x ‐based TFSCs using SCAPS‐1D simulations. The optimization process involves key factors such as absorber layer thickness, defect densities, electron and hole transportation layers (ETLs and HTLs), and back contact work functions. The results indicate that Se _0.75 Te _0.25 solar cells achieve a significant improvement in PCE with optimized device architecture. Specifically, cells incorporating MoO _x as an HTL demonstrate a PCE of 21.94%. Interestingly, the HTL‐free cells, optimized for back contact work function, accomplished a comparable PCE of 21.59%, highlighting the feasibility of eliminating the HTL layer without compromising efficiency. To validate our approach, a global optimization of the HTL‐free structure was performed using a single‐objective genetic algorithm. The findings suggest that optimizing back contact material, defect density, and absorber thickness can lead to high‐efficiency Se _0.75 Te _0.25 ‐based TFSCs for terrestrial applications.

Lead-free perovskite halides have attracted significant attention from the scientific community as these materials are environmentally friendly and possess higher optoelectronic performance; however, their structural analysis still requires systematic investigation. The potential for improved stability and efficiency in optoelectronic applications makes potassium-based halide perovskites noteworthy. Potassium-based halide perovskites offer lower toxicity and are a safer option for environmentally friendly technology. In this work, we have assessed in detail the physical attributes of K ₃ XI ₆ (X[ ] [ ] [ ]In, Ga). For analyzing the electron-ion exchange correlation effects, the modified Becke–Johnsons (mBJ) is used. To check the stability of these halides, several parameters are computed. The second-order stress–strain energy equations are employed for the computation of elastic constants of K ₃ XI ₆ (X[ ] [ ] [ ]In, Ga). The mechanical stability is checked via Born’s stability criteria. Sound velocities for K ₃ XI ₆ (X[ ] [ ] [ ]In, Ga) along three crystallographic planes [100], [110] and [111] are also analyzed. Direct bandgaps of 2.12[ ]eV and 1.72[ ]eV are attained for K ₃ InI ₆ and K ₃ GaI ₆ as revealed via their electronic properties. Both materials report large optical conductivity and polarization in the visible and UV region and computed bandgaps highlight their applicability for advanced optoelectronic technological applications. Thus, the overall findings demonstrate that K ₃ XI ₆ (X[ ] [ ] [ ]In, Ga) materials are excellent contenders for low-toxicity and energy-related applications.

In the renewable energy industries, halide double perovskite compounds have become revolutionary materials because of their higher power conversion ability and environmental friendliness. Therefore, in this paper, we have scrutinized the physical traits of halide double perovskites K ₂ TlInX ₆ (X[ ] I, Br) using a DFT-based code as Wien2K. The ground state parameters for K ₂ TlInX ₆ (X[ ] I, Br) are analyzed using the GGA functional, whereas the mBJ is employed to analyze the rest of the physical properties. The structural, dynamic and thermodynamic stability are ensured through optimization plots, phonon plots, negative formation energies and tolerance factor for K ₂ TlInX ₆ (X[ ] I, Br). The studied halides show complete mechanical stability. The elastic anisotropy is analyzed using the ELATE software. Indirect bandgap of 1.43 eV and 2.41 eV are revealed via electronic properties of K ₂ TlInI ₆ and K ₂ TlInBr ₆ . A comprehensive assessment of the optical attributes of K ₂ TlInX ₆ (X[ ] I, Br) is done via Kramer’s complex equations. Moreover, the transport attributes are evaluated using the BoltzTraP code. By analyzing K ₂ TlInX ₆ (X[ ] I, Br)’s structural, mechanical, electrical, optical and transport properties, it is concluded that these halides are feasible to be employed in thermoelectric and optoelectronic devices.

Countries like Saudi Arabia receive abundant sunshine with exceptionally high solar irradiance. High temperatures in desert regions and the sunray angle dependence of solar modules are some of the key challenges of conventional solar cells. Dye-sensitized solar cells present a compelling alternative with the simple cell design and use of non-toxic materials without angle dependence, but their performance hinges on the solid redox mediators used for dye regeneration. These mediators must have an electrical conductivity (σ_25°C) of more than 10⁻⁴ S cm⁻¹ with an activation energy of less than 0.3 eV for device application. Our work focused on novel solid Co(II/III) redox mediators using cobalt complexes and LiClO₄ in different matrices: pure PEO (an abbreviation for poly(ethylene oxide) with its redox mediator as M1), a [PEO–SN] blend (M2A and M2B with ethylene oxide to lithium ions molar ratio of 112.9 and 225.8, respectively), and pure SN (an abbreviation for succinonitrile with its redox mediator as M3). Impedance spectroscopy was the key technique, showing M1 and M2 behave like a mediator explainable with an (R₁–C)-type circuit, while M3 is explainable with an (R₁ − [R₂‖C])-type circuit. M3 achieved the highest value of σ_25°C with 2 × 10⁻³ S cm⁻¹, while M1 had the lowest σ_25°C, 3 × 10⁻⁵ S cm⁻¹. M2 achieved an optimal balance with σ_25°C of 4 × 10⁻⁴ S cm⁻¹ (M2A) and 1.5 × 10⁻⁴ S cm⁻¹ (M2B). M2 exhibited a remarkably low pseudo-activation energy of 0.042 eV and a Vogel–Tammann–Fulcher behavior ideal for consistent performance across temperatures. In contrast, M1 and M3 showed higher Arrhenius-type activation energies (>0.74 eV) in their solid states. These results correlated with those of the XRD, FT-IR spectroscopy, XPS, SEM, DSC, and TGA analyses. Ultimately, the [PEO–SN] blend emerges as a robust matrix, enabling the combination of high conductivity and low activation energy needed for a durable device in harsh environments.

The optoelectronic applications of cesium-based double perovskites are significant because of their tunable band gaps, stability, and eco-friendliness. In this paper, we scrutinized the physical properties of Cs ₂ ZTlI ₆ ([ ], Rb) using the FP-LAPW technique. The volume optimization, tolerance factor and ground state energies for Cs ₂ ZTlI ₆ ([ ], Rb) are computed to check the structural integrity, meanwhile, the formation energies are computed to ensure thermodynamic stability. The ionic bonding nature is revealed through the electron density contour plots. The elastic constants for Cs ₂ ZTlI ₆ ([ ], Rb) are calculated using second-order stress-strain energy equations. The band structure profiles for Cs ₂ KTlI ₆ and Cs ₂ RbTlI ₆ depict direct band gaps of 1.07[ ]eV and 1.22[ ]eV, respectively. Both Cs ₂ KTlI ₆ and Cs ₂ RbTlI ₆ have high polarization in the visible and UV ranges, as evidenced by their optical properties. Their large optical conductivity and considerable polarization throughout these spectra, together with the estimated band gaps, make them ideal for photovoltaic applications. Furthermore, the moderate ZT values and large power factor endorsed their potential as ideal candidates for thermoelectricity.

In this paper, we have used the spin-polarized computations to evaluate the physical properties of A ₂ BMoI ₆ ([ ]/Rb; [ ] Rb/Li). Minimum ground state energy for both compounds is attained via volume optimization curves. Both materials offer thermodynamic and structural stability as verified via tolerance factor and negative formation energies. The computed elastic constants via compliance matrix ([ ], C[ ], C[ ]) fully support the Born’s stability measures. The mechanical characteristics of K ₂ RbMoI ₆ show ductility, whereas Rb ₂ LiMoI ₆ shows brittleness. High melting temperatures are also obtained for K ₂ RbMoI ₆ and Rb ₂ LiMoI ₆ which implies strong atomic strength of the atoms with the crystal lattice. The electronic characteristics of K ₂ RbMoI ₆ and Rb ₂ LiMoI ₆ in both spin channels demonstrate semiconducting behavior. Both materials tend to absorb more incident radiations in the UV region as revealed through their optical characteristics. Thermoelectric properties of A ₂ BMoI ₆ ([ ]/Rb; [ ] Rb/Li) revealed a high ZT value for both studied compounds, which infers that these materials are efficient for converting waste heat into electricity.

Defected hydrides are crucial to investigate for hydrogen storage purposes because they possess a higher tendency to improve hydrogen absorption and desorption by introducing active defect sites, which helps in decreasing activation energies and enhancing kinetics. In this paper, we have analyzed the effects of the physical traits of Cs ₂ AlInH ₆ by creating a vacancy at the cation site. The analysis of the structural integrity revealed that Cs ₂ AlInH ₆ possesses higher stability than Cs ₂ InH ₆ . The computed formation energies indicate that both hydrides are thermodynamically stable. The mechanical properties for both hydrides are computed via Thomas Charpin’s approach. The Debye and melting temperature signify that Cs ₂ AlInH ₆ possesses stronger atomic interactions and higher endurance to external heat as compared to Cs ₂ InH ₆ . An indirect bandgap of 1.64[ ]eV is reported for Cs ₂ AlInH ₆ , and Cs ₂ InH ₆ demonstrates metallic characteristics as evaluated by the electronic properties. A higher level of electronic interactions in the visible region is reported for Cs ₂ AlInH ₆ , whereas for Cs ₂ InH ₆ , high polarization is noticed in the infrared region, which is described via the optical analysis. The hydrogen storage properties reveal that the removal of the Al atom has significantly enhanced the gravimetric and volumetric densities, while lowering the desorption temperature of the material, making it more efficient and practical for hydrogen storage and renewable energy applications.

A solid Co²⁺/Co³⁺ redox mediator (solid electrolyte) with an electrical conductivity (σ_25°C) greater than 10⁻⁴ S cm⁻¹ is reported for a dye-sensitized solar cell in the harsh weather of Gulf countries.